Can protein biomarkers provide an index of coronary artery calcification in patients with Type 2 diabetes?

OBJECTIVES

By exploring differences between patients with high and low coronary artery calcification score (CACS), a plasma protein biomarker might be identified as an alternative to CACS screening.

METHODS

We selected stored samples (12 per group) from a cohort study of patients with Type 2 diabetes and CACS >1000 or <100 Agatston units, with matching for age, BMI, blood pressure, lipids and lipoproteins and fibrinogen. Multiplex, immunobead-based assay or ELISA measured 18 cardiovascular-related protein biomarkers. SELDI-TOF mass spectrometry (MS) screened for proteins differing significantly between high and low CACS.

RESULTS

Only monocyte chemotactic protein-1 was higher in the high compared with the low CACS group but concentrations overlapped appreciably. On SELDI-TOF MS, several mass/charge ratio peak intensities significantly discriminated high and low CACS but these differences were not confirmed in larger samples from the cohort.

CONCLUSIONS

Plasma protein biomarkers are unlikely to provide an effective alternative to measurement of CACS.

Glucose Production in the Human Placenta

Glucose transfer from mother to fetus by placental facilitated diffusion is the dominant mechanism by which the fetus acquires glucose. In small for gestational age pregnancies, fetal glucose concentrations tend to be lower than normal and this persists following delivery. GLUT1 is the major glucose transporter in human placenta but there is no evidence of GLUT1 deficiency as a cause of the lower fetal glucose concentration in small for gestational age pregnancy. The physiological and pathological roles of the other glucose transporters (and there are 14 currently described) are unknown. In recent years, the possibility has been raised that the placenta is itself capable of supplying glucose for fetal needs. This hypothesis derived from glucose isotope studies in normal pregnancy, where dilution of glucose isotope was demonstrated in blood samples taken from the fetal circulation during intravenous infusion of glucose isotope in the mother. Although other gluconeogenic enzymes were known to be present, the placenta was previously considered incapable of glucose secretion because it lacked functional glucose-6-phosphatase. Recent studies, however, have suggested that specific glucose-6-phosphatase may be present in placenta but it may be the product of a different gene from conventional hepatic glucose-6-phosphatase. The presence of the specific transporters necessary for glucose-6-phosphatase activity is currently being investigated. The role of placental glucose secretion in normal and growth-restricted pregnancies is an area of current study.

Alcohol ingestion lowers supine blood pressure, causes splanchnic vasodilatation and worsens postural hypotension in primary autonomic failure

Patients with pure autonomic failure (PAF) and multiple system atrophy (MSA) may complain of feeling light-headed after alcohol ingestion particularly on assumption of the upright posture. The reasons for this have not been investigated. We therefore studied the effects of oral alcohol (40% vodka in sugar-free orange juice) and placebo (juice only) on the systemic and regional (including superior mesenteric artery, SMA) blood flow in nine patients with PAF and six patients with MSA. After alcohol, there was a fall in supine blood pressure (BP) and vasodilatation in the SMA but no change in cardiac output, or forearm muscle and cutaneous blood flow in either PAF or MSA; BP fell further during head-up tilt with no changes in levels of plasma catecholamines. After placebo, there were no changes while supine. We conclude that alcohol lowers supine BP and dilates the SMA with no change in muscle or cutaneous blood flow. Alcohol also enhances the fall in BP during head-up tilt. This may explain the symptoms experienced by PAF and MSA patients after alcohol.

Cardiovascular and hormonal responses to liquid food challenge in idiopathic Parkinson's disease, multiple system atrophy, and pure autonomic failure

We investigated the effect of a balanced liquid meal on blood pressure (BP) and heart rate (with patients supine and during head-up tilt), and on levels of plasma catecholamines, glucose, and insulin, in patients with idiopathic Parkinson's disease (IPD), multiple system atrophy (MSA), pure autonomic failure (PAF), and in healthy subjects (controls). After food, supine BP fell in IPD, but to a greater extent in MSA and PAF. In controls, BP was unchanged. Head-up tilt did not lower BP in IPD and controls, but there was a postprandial fall to lower levels in both MSA and PAF. Plasma norepinephrine levels rose in IPD pre- and postprandially during tilt, but were unchanged in MSA and PAF. These data suggest that in IPD, food causes a smaller fall in supine BP than in MSA and PAF. In IPD, as in controls, food does not induce or unmask postural hypotension, unlike in MSA and PAF, in which BP falls to even lower levels. There are therefore differences in the responses to food ingestion between these groups. This may be of value in separation of these disorders at an early stage.

Effects of oral alcohol on superior mesenteric artery blood flow in normal man, horizontal and tilted

1. The cardiovascular effects of oral alcohol (0.5 g/kg body weight diluted to 300 ml in sugar-free orange juice) were compared with those of placebo in 10 normal subjects. Measurements were made while the subjects were supine and horizontal for 45 min and after 10 min of 45 degrees head-up tilt. 2. After alcohol, plasma alcohol levels rose from 1.9 +/- 1.3 to 61.6 +/- 6.5 mg/100 ml. After placebo, plasma alcohol levels did not increase. After alcohol and placebo, supine blood pressure was unchanged; heart rate, both supine and during tilt, rose after alcohol only. 3. After alcohol, superior mesenteric artery and digital skin blood flow increased and calculated vascular resistances fell. There was no change after placebo. 4. Forearm blood flow, forearm vascular resistance and cardiac index did not change in either phase, except for a fall in cardiac index during tilt but only after alcohol. 5. In conclusion, the acute ingestion of 0.5 g of alcohol/kg body weight in normal subjects raised heart rate and actively dilated the superior mesenteric artery and digital skin vessels. There was no effect on blood pressure, cardiac output and skeletal muscle vascular tone. During head-up tilt after alcohol, there was a tendency for blood pressure to fall with a compensatory rise in heart rate.

The vertebral canal: I. Nutrition and development, an archaeological study

The lumbar vertebral canal was measured in adult spines from two archaeological populations, and was compared with four physiological stress indicators, (cribra orbitalia, porotic hyperostosis, dental hypoplasia and Harris lines). The stature of 38 juvenile skeletons and their canal size were compared with those of the adults. By 4 years of age the midsagittal diameter and the area of the vertebral canal was fully mature and the mean interpedicular diameter 87% of adult size. There was a differential pattern of growth, with the proximal spine maturing first. The trefoil shape was not seen at L5 before puberty. Dental hypoplasia correlated with a small interpedicular diameter at L1, L2 and L3, and Harris lines with a small midsagittal diameter at L1, L3 and L5, a small area at L5 and a more trefoil canal at L4 and L5. There is evidence that adverse environmental factors are associated with the development of spinal stenosis.